Some 12 different types of vehicle have been bought by the force over the past four years. The armoured Insignia costs around seven times more than any of these.

The lack of space has been blamed for back and neck injuries suffered by officers wearing bulky body armour and belts loaded with kit.

It has prompted a safety review on the pricey patrol cars.

The Belfast Telegraph yesterday revealed 125 officers had filed complaints over injuries sustained while on duty in them.

It is understood a block has been put on buying more Insignias for the time being.

Complaints centre on the interior space of the hatchbacks.

Officers say it is greatly reduced by anti-ballistic protection fitted to the doors and windows.

Many officers believe the vehicles are unfit for purpose because of difficulties getting in and out while wearing full body armour and a belt holding a gun and magazine, baton, CS spray, handcuffs and first aid pouch.

DUP MP Jim Shannon - who first raised the issue in the Commons last year - said he had been inundated with calls from PSNI members concerned for their health and safety.

"The Insignia hatchbacks were completely unworkable - almost £100,000 was spent armouring each of the 90 cars that were too small to use in the end," he said.

"It was very clearly a safety issue for officers; they couldn't arrest anyone and put them in the back of the car because of the lack of space.

"They had to ask for a van to be sent down to pick the arrested person up, which is a ludicrous thing."

Assistant Chief Constable Alan Todd said: "The models in question are widely and successfully used across Northern Ireland.

"Like every armoured vehicle, the model in question represents a compromise between comfort and protection.

"They have successfully withstood terrorist attack and saved lives, going a long way to justifying their specification and manufacturing costs.

"The organisation is always exploring new alternatives to meet the needs of our varied operational environments and continues to do so in the interests of keeping our officers safe."